Electrical apparatus



Nov. 15, 1938. H s GATE-S 2,137,082

ELECTRICAL APPARATUS V Filed Feb. 6, 1956 a; s Hen/y 5. Gafes.

Patented Nov. 15, 1938 iJNITl-:D STATES PATENT OFFICE 2,131,082 ELECTRICAL APPARATUS Sylvania Application February s, i936, serial 10.62.663

s claim. (ci. ecc- 5) This intention relates to electrical apparatus and particularly to transformer grounding Switches.

in the operation of electrical apparatus such 5 as transformers, it is riesirable to disconnect the transformer from the power circuit when repairs or changes are te be matie and to so ground the eer'ier that the transformer is not egairi connected to the circuit until the repairs or changes l have bee mede. .it is also desirable to provide a grounding switch such as cannot be operated to its ground oositiou when the transformer or feeder is energized. j

Heretoore riierent types of grounding switches l have eo deveioped whereby the switch carinot be operated. to its grounding position when the transformer or feeder is energized. These grounding switches, however, require complicated mechouicel one electrical locking and switching 2o mohorrisms'or proviriirrg the desired operation the disconnected or operi position to the grosseins position.

object of this invention is to provide a switch to couriect the conductors to the ,when the conductors ere disconnected .th'st connecting the conductors to the transformer windings. ,y

A further object of this invention is to provide for translating rotary movement into linear movement to reciprocally actuate the switch members of a three position grounding switch in connecting the conductors of an electrical circuit to the windings of a transformer or to grouncl and for disconnecting them therefrom and. to provide for preventing a movement of the switch members to connect the conductors to ground 5c when the conductors are disconnectedwithcut A first connecting the conductors to the transformer windings.

Otherobjects willbe apparent from the followinguescription when taken in conjunction with the accompanying drawing, in which- Figure i is a schematic view illustrating the three phase transformer, its primary and secondary circuits and a three-phase grounding switch connected in one of the circuits,

Fig. 2 is en elevational View partly in section oi a grounding switch enel its operating mecha.- nism mounted Within a suitable switch casing, the front cover of which is shown removefi, and

Fig. 3 is a sectional View taken along the-line illm of Fig. 2, showing a portion or' the switch Vtunel its operating mechanism.

Lilie reference numerals in the different gures of the chewing denote like parts.

This invention is illustrated as embodied in et circuit in which it is desired to protect en elecn tricai apparatus such as a transformer.

Referring to the drawing and Fie'. l thereof in particular, this invention is iliustrateii in o circuit in which e. transformer it bovine low volts/se windings and i?! is connected by means of circuit hreeker il to the three conductors oi a low voli-eee threephose circuit 6, l enel The high voltage Wndiugs itl, l@ and El? of the trous'- iormer it are connected through e three-phase grounding switch, shown generelle et it, to loisir volto-,e i 1 conductors itl, euri circuit breaker to e. voltege power supo/v source.

ic. this embodiment, the actuating mechanism ariel switch members of the grounding switch iii ere positiouecl iu the enclosing cese es shown The enclosing cese suitable tuig ori the cose or a transformer, in Fig. 3 or on e, Well, .in practice, the bottom, sides, basis, iront enel top ci the cese are so abrceteci that the assembled case is leak proof suitebie for containing au. insulated liquid where desired. A valve :l may be positioneo. in the bottom ci the cese 23 for withdrawing the insulating liquid in which the grounding switch is ordinarily immersed.

The grounding switch I8 is provided with three movable switch members 25, 2t and 2?! corrieri in bushings 28, 2Q and 3U, respectively, which are suitabiy mounted on e. bushing bridge 3i. The ends ci" the bushing bridge 3l are attached in a suitable manner to racks 32 and. 33, respectively,

respectively. ,The contact members 31, 38 and 39 are mounted on insulating bushings 40, 4I and t2 that are suitably mounted on the bushing bridge 43, the ends of which are bolted or otherwise permanently attached to the walls of the case 23.

As'shown in Fig. 2, the contact members 31, l38 and 39 are suitably connected as by conductor straps 44, 45 and 46 through the terminal bushings 41, 48 and 49 that extend through the back of the case 23 and the transformer case 24 containing the windings I5, I6 and I1 to which the transformer terminal contact members 31, 38 and 39 are connected.

The lower ends of the movable switch members 25, 26 and 21 are provided with terminals 50, 5i and 52 that are adapted to slidingly engage line terminal contact members 53, 54 and 55, respectively. The contact members 53, 54 and 55 are carried byinsulating bushings 56, 51 and 53, respectively, that are suitably mounted on the bushing bridge 59, the ends of which are bolted to the walls of the case 23. The contact members 53, 54 and 55 are connected by conductor strapsA 60, 6| and 62, respectively, through the line terminal bushings 63, 54 and 65 mounted in the bottom of the case and through the main line terminal' bushing 66 to the conductors I9, 20 and 2i of the power source.

In order that the movable switch members 25, 26 and 21 may be electrically connected at all times to the conductors i9, 2U and 2i, the line terminal contact members 53, 54 and 55 are in the form of` an elongated knife switch of such length that at no time during a movement of the movable switch members 25, 26 and 21 will the sliding electrical engagement between the contact members 5G, 5i and 52 and the line terminal contact members 53, 54 and 55, respectively, be broken.

in order to ground the conductors i9, 20 and 2i when the transformer i ii is not energized, contact members 6i, adapted to engage the ground terminal Contact members 10, 1i and 12 when the switch is actuated to ground position, are provided on the lower end of movable switch members 25, 26 and 21. The ground terminal contact members 1U, 'il and 12 are carried by the insulating bushings 13, 14 and 15 suitably mounted through the bottom of the case 23 and are electrically connected therethrough "to the short circuiting bar 5 and the common ground 16.

in order to actuate the racks 32 and 33 to move the movable switch members 25, 26 and 21, gear sectors 11 and 13 adapted to engage the racks 32 and 33, respectively are suitably nounted on shafts 19 and 86 mounted through stuffing glands 8| and 82, respectively, positioned inthe sides of the case 23. A segment 83 provided with a,

counter-balance wheel 64 to counter-balance the weight of the gear section 11 and to provide for maintaining the movable switch members 25, 26 and 21 in a desired position is also provided on the shafts 19 and 36.

In order to lock the movable switch members 25, 26 and 21 to close acircuit from the line terminal contact members to the transformer terminal contact members when thevtransforml er l0 is energized, an electrical interlock 85 is provided in the case. The windings of the interlock are electrically connected through conductors 86 and 81, as viewed in Fig. '1, to the transformer l0.

As shown inFigs. 2 and 3, the armature 3,1 of the interlock 85 is in the form of an extended arm. When the transformer and consequently the windings of the interlock are energized, the armature 91 is adapted to engage one of the grooves 88, 88' and 88", disposed about the poriphery of the segment 33 to lock the actuating mechanism.

Adjustable stops 33 and 33 are provided in the case to limit the path of the movement of the movable switch members 25, 26 and 21 in response to a movement of the actuating mechanism, a rod 9i being provided on the racks 32 and 33 and projecting above and below the racks for abutting the stops 33 and 93 when the movable switch members are in open position and ground position", respectively.

As viewed in Figs. 2 and 3 of the drawing, the three-position grounding switch I3 is in transformer position". That is, the movable switch members 25, 26 and 21 bridge theline terminal Contact members 53, 54 and 56 and the transformer terminal contact members 31, 38 and 33, respectively, to close a circuit from the power source to the transformer i6 through the circuit breaker 22 and conductors i3, 23 and 2l. In this position the windings of the electrical interlock 85 are energized and the armature 91 is actuated to enter groove 88 of the segment 83 to lock the actuating mechanism in the transformer position. i

In lorder to actuate the switch members 25, 23 and 21 to either the ground position wherein the movable switch members bridge the line terminal contact members 53, 54 and 55fand the ground terminal contact members 16, 1| and 12 to ground, or to the disconnect position in which the rod 9i abuts the stop 83, circuit breakers i4 and 22 must be opened to deenergize the transformer l0 and deenergize the windings of the interlock 85.

When the windings of the interlock V85 are deenergized the armature arm 31 is withdrawn from groove 88 and the movable switch members 25, 26 and 21 may be moved to disconnect position by actuating the shafts 19 and 83 by anysuitable means such as by an operators handle or a rope mechanism (not shown). In turning the shafts 19 and 80 in clockwise direction, the segments 83 and the gearvsectors 11 and 18 are rotated in a clockwise direction as viewed in Fig. 3 to actnate th'e racks 32 and 33 to move in a vertical direction in their guides (not shown).

The linear movement of the racks 32 and 33 causes the assembly of the movable switch members 25, 26 and 21 on the bushing bridge 3i to ao move in a vertical direction that the contact members 34, 35 and 36 on the upper ends of the movable switch members disensae the transformer terminal contact members 31, 33 and 33, respectively, the contact members 53, 5i and 52 on the lower end of the movable switch members maintaining their electrical engagement with the line terminal contact members 53. 34 and 55. The vertical movement of the movable switch members to the "disconnect position is limited as hereinbefore described by the stops 33 positioned on the walls of the case 23.

In operation, when it is desired to ground the feeder to the transformer, the shafts 13 and 33 are rotated in a counter-clockwise direction, as viewed in Fig. 3, to actuate the movable switch members from their disconnect position" hereinbefore described.

In moving from the disconnect position" to the ground position"I the movable switch members move progressively from the open circuit or dilconnect position to and through the ,"transformer position, to the ground position.

If either of the circuit breakers Il or 22 are closed when the movable switch members are actuated to the transformer position, the transformer I0 and the windings of the electrical interlock 85 become so energized that the armature 91 of the interlock is) moved into the groove 88 of the segment 83f" to lock the switch in transformer position.v Before the movable switch members can then me moved to the ground position circuit breakers I4 and 22 must be opened, deenergizing the transformer I0 and the windings of the electrical interlock 85.

When the interlock 85 is thus deenergized, the shafts 19 and 80 may be rotated in a counterclockwise direction, as viewed in Fig. 3, to actuate the movable contact members to the ground position where contact members 51 on the lower ends of the movable switch members 25, 26 and 2l engage the ground terminal contact members 10, Il and l2 to close a circuit from the conductors i9, 2li and 2| to the ground 16.

It is -thus evident that with the grounding switch of this invention the feeder cannot be grounded until after the transformer is deenergized. It is further evident that the mechanism of the grounding switch hereinbefore described is such-that the desired positions of the switch may be obtained through reciprocal movement of the movable contact members and that the desired operation of connecting in transformer position before entering ground position from an open circuit or disconnect position is attained without the aid of mechanical interlocks. t

Further advantages are obtained in the grounding switch of this invention by translating rotary movement necessary in actuating the mechanism into linear movement to obtain the reciprocating movement of the movable' switch members,

since the actuating mechanism may thereby be simplified. By providing the reciprocating movement, the movable contact members can be operated from their open circuit or disconnect position only in a direction to close the switch in its transformer position, from which position it cannot be operated to the "ground position unless the transformer is deenerglzed. This progressive movement of the movable switch members accomplishes the desired result of preventing the operation of the switch from its open circuit position except toward its "transformer position.

Although this invention has been described with reference to a particular embodiment thereof other and various modifications thereof are possible. It is, therefore, not to be restricted except insofar as is necessitated by the prior art and the scopeof the appended claims.

I claim as my invention: c 1. In a transformer grounding switch, in combination, a, transformer terminal .contact member, a line terminal contact member, a ground contact member, a switch disposed for movement to electrically connect the line terminal contact member to the transformer terminal contact member or the line terminal contact member to the ground contact member, the switch being also disposed for movement to open circuit posi-.- tion where it is in contact with the line terminal contact member but does not bridge a plurality of contact members, means for actuating the switch member, the ground'and line terminal contact members being so disposed that as the switch is moved progressively from open cir' cuit position it bridges the transformer and line terminal contact members and then ground and line terminal contact members which positions aregenerally designated transformer and ground positions respectively, and means cooperative to lock the switch in transformer position if the transformer is energized.

2. In a transformer grounding switch, in combination, a transformer terminal contact member, a line terminal contact member, a ground contact member, a switch disposed for movement to electrically connect the line terminal contact member to the transformer terminal contact member or the line terminal contact member to the ground contact member, the switch being also disposed for movement to open cir uit position where it is in contact with the line erminal contact member but does not bridge a plurality of contact members, means for limiting`the extent of the movement of the switch member in the direction of the open circuit position, the transformer terminal contact member being disposed between the said limiting means and the ground contact member, means for so actuating the switch member that it progressively moves from the open circuit position to bridge the transformer and line terminal contact members and then bridge the yground and line terminal contact members which positions are generally designated transformer and ground positions respectively, and means cooperative to lock the switch in' transformer position when the transformer and line terminal contact members are bridged if the transformer is energized.

3. In a transformer-grounding switchlfor electrically connectingl the transformer to line or line to ground, in combination, a plurality of contact members, the contact members being electrically connected to ground, line and transformer respectively, a switch member for bridging the contact members disposed for reciprocating movement to different positions including an open circuit position where it does not bridge a plurality of contact members, means for limiting the extent of the movement of the switch member in the direction of the open circuit position, the contact member connected to the transformer being disposed between the said limiting means and the contact member connected to the ground,

means for actuating the switch member, said actrically connecting the transformer to line or line to ground, in combination, a plurality of contact members, the contact members being electrically connected to ground,vline and transformer respectively, a switch/"member for bridging the contact members disposed for reciprocating movement to different positions yincluding an open circuit position where it does not bridge a plurality of contact members, means for limiting the extent of the movement of the switch member in the direction of the open circuit position, the contact member connected to the transformer being disposed between the said limiting means and the contact member connected to the ground, means for actuating the switch member, said actuating means being disposed to move the switch member progressively from the open circuit position to bridge the contact members electrically connected to the transformer and line respectively and then to bridge the contact members electrically connected to the ground and line respectively which positions are generally designated transformer and ground positions respectively, means disposed between the actuating means and switch member for translating rotary movement into linear movement, and means cooperative to lock the switch in transformer position if the transformer .is energized.

5. In a transformer grounding switch for electrically connecting the transformer to line or line to ground, in combination, a plurality of contact members, the Contact members being electrically connected to ground, line and transformer, respectively, a switch member for bridging the contact members disposed for reciprocating movement to different positions including an open circuit position where it does not bridge a plurality of contact members, means for actuating the switch member, said actuating means being disposed to move the switch member progressively in the following sequence open", transformer and ground, the line Contact member being so disposed that the electrical connection between the switch member and the iine contact member is maintained for all positions of the switch member including open circuit position, and means cooperative to lock the switch in transformer position when the transformer and line terminal contact members are bridged if the transformer is energized.

5. In a transformer grounding switch for electrically connecting the transformer to line or line to ground, in combination, a plurality of Contact membersthe contact members being electrically connected to ground, line and transformer, respectively, a switch member for bridging the contact members disposed for reciprocating movement to different positions including an open circuit position where it is in contact with the line Contact member but does not bridge a plurality of Contact members, means for limiting the extent of the movement of the switch member in the direction of the open circuit position, means for actuating the switch member, said actuating means being disposed to move the switch member progressively from the open circuit position to bridge the contact members electrically connected to the transformer and line, respectively, and then to bridge the contact members electrically connected-to the ground and line, respectively, which positions are generally designated transformer and ground positions, respectively, means comprising a rack and gear segment cooperating therewith disposed between the actuating means and switch member for translating rotary movement into iinear movement, and means cooperative to iocl; the switch in t nsiormer position if the transformer energized.

HENRY S. GATES. 

